I have b1 usa visa Upto 2014. Owens and came back. Can I go now

I have b1 usa visa Upto 2014. Already I went and attended one Business meeting and came back to India within 15 days. Now I changed company. Now got opportunity to attend meeting once again. Can I attend? pls answer my question in detail. And in my visa they not below the column visa type R B1/B2 what is the meaning of R B1/B2.

Tq

Venu